1. Field of the Invention
The invention relates generally to optical waveguides and methods for forming such optical waveguides.
2. Brief Description of Related Technology
The demand for continuous increase in transmission speed, data capacity and data density in integrated optical and optoelectronic circuits has been the motivating force behind numerous innovations in areas of broadband communications, high-capacity information storage, and large screen and portable information display. Although glass optical fibers are routinely used for high-speed data transfer over long distances, they are inconvenient for complex high-density circuitry because of their high density, poor durability and high cost of fabrication for complex photonic circuits. As such, polymeric materials hold great promise for constructing cost effective, reliable, passive and active integrated components capable of performing the required functions for integrated optics.
Generally, the invention provides a method for producing an optical waveguide that includes the steps of: (a) forming a core structure, the core structure including an at least partially cured core composition, on a master defining a waveguide pattern; (b) applying over the top of the core structure and the master a cladding layer including a liquid cladding composition; (c) curing the cladding layer to form a core/cladding combination; and (d) removing the core/cladding combination from the master so as to expose at least a portion of the core structure, wherein the refractive index of the cured core composition is at least 0.05 percent higher than the refractive index of the cured cladding composition.
In another embodiment, the invention relates to a method of producing an optical waveguide that further includes the step of: (e) forming a second cladding layer over the exposed portion of the at least one core structure, thereby burying the at least one core structure.
In another embodiment, the invention relates to a method of producing an optical waveguide that includes the steps of: (a) forming a core structure, the core structure including an at least partially cured core composition, on a master defining a waveguide pattern; (b) applying over the top of the core structure and the master a cladding layer including a liquid cladding composition; (c) curing the cladding layer to form a core/cladding combination; and (d) removing the core/cladding combination from the master so as to expose at least a portion of the core structure, wherein the refractive index of the cured core composition is at least 0.05 percent higher than the refractive index of the cured cladding composition.
In another embodiment, the invention relates to a method for producing an optical waveguide core structure that includes the steps of: (a) applying a core composition to a substrate defining a waveguide core pattern; (b) removing a portion of the core composition from an exposed surface of the filled waveguide core pattern; and (c) at least partially curing the core composition to form a core structure.
In another embodiment, the invention relates to a method for producing an optical waveguide which includes the steps of: (A) forming at least a two layer film having at least one layer of core material formed over at least one layer of cladding material; and (B) forming at least one waveguide feature in at least the at least one core layer of the at least two layer film, wherein the refractive index of the core material is at least 0.05 percent higher than the refractive index of the cladding material.
In another embodiment, the invention relates to a method of producing an optical waveguide wherein the at least one waveguide feature formed in step (B) is produced using a cutting technique.
In another embodiment, the invention relates to a method of producing an optical waveguide which further includes the step of: (C) forming a second layer of cladding material over an exposed surface of the core layer.
In another embodiment, the invention relates to an optical waveguide comprising: core structures formed from a core polymer produced by the polymerization of a core material comprising at least one cyclic olefin monomer and/or at least one crosslinking monomer; and at least one cladding structure produced by the polymerization of a cladding material comprising at least one cyclic olefin monomer and/or at least one crosslinking monomer, wherein the refractive index of the core material is at least 0.05 percent higher than the refractive index of the cladding material.
In another embodiment, the invention relates to an optical waveguide wherein the core and cladding materials are polymerized by a mass polymerization process using a combination of at least one pro-catalyst and at least one co-catalyst.
In another embodiment, the invention relates to a composition for forming either the core or cladding portion of an optical waveguide comprising at least one norbornene-type monomer and/or at least one crosslinking monomer and at least one co-catalyst, wherein polymerization is achieved by the addition of at least one pro-catalyst.
In another embodiment, the invention relates to a composition for forming either the core or cladding portion of an optical waveguide comprising at least one norbornene-type monomer and/or at least one crosslinking monomer and at least one pro-catalyst, wherein polymerization is achieved by the addition of at least one co-catalyst.
The invention is advantageous in that it provides compositions which permit the formation of optical waveguides having better performance qualities such as, for example, a difference (xcex94n) in the refractive index of the core material versus that of the clad material of at least about 0.00075 (i.e., 0.05% where the clad or cladding material has a refractive index of about 1.5) for over a broad wavelength range (e.g., about 400 to about 1600 nm); lower intrinsic optical loss (lower than about 1 dB/cm and in some cases lower than about 0.5 dB/cm); a high glass transition temperature (Tg) (e.g., in one embodiment at least about 150xc2x0 C., in another embodiment at least about 250xc2x0 C., and in some cases at least about 280xc2x0 C).
The disclosed methods for forming optical waveguides are advantageous in that they permit the formation of improved optical waveguides. For example, the core-first methods permit the formation of optical waveguides with a reduction and/or elimination in the occurrence of xe2x80x9cswellingxe2x80x9d between layers (see FIGS. 5A and 5B for a photographic depiction of xe2x80x9cswellingxe2x80x9d). In another example, the fill-and-remove methods described below permit the formation of isolated, buried-channel waveguides that have surfaces smoothed by surface tension of the core material, rather than machined, which improves signal loss. Thus, another aspect of the invention is optical waveguides produced by the methods of the invention.
The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail one or more illustrative embodiments of the invention, such being indicative, however, of but one or a few of the various ways in which the principles of the invention may be employed.